[2] On Broadway, she portrayed Molly Belmont in By the Beautiful Sea (1954), and Janice Dawson in Happy Town (1959).

Her best-known role was that of Carol Porter, one of the daughters in the one-season situation comedy The Tom Ewell Show (1960–61).

Her other television work consisted of appearances in comedy shows (Ensign O'Toole, Father Knows Best, The Adventures of Ozzie and Harriet, Leave It to Beaver), McHale's Navy and military/action shows (Steve Canyon, Whirlybirds, Harbor Command), westerns (Wagon Train, The Tall Man), and dramas (Westinghouse Desilu Playhouse, Tightrope!, Dragnet).

Cynthia, then still known as Cindy Robbins, married New Jersey singer-songwriter Tommy Leonetti on November 27, 1965, in Beverly Hills, California.

[7] The two of them, plus her young daughter, moved to Sydney, Australia, and lived there for the remainder of the 1960s and for most of the 1970s, before returning to America in the late 70's.